Characterisation of microporous and mesoporous materials by the adsorption of molecular probes: FTIR and UV-Vis studies

This contribution describes with a few, properly selected, examples the spectroscopic characterisation of acid, base and redox centres in microporous and mesoporous molecular sieves. FTIR studies of the adsorption of molecular probes that lead to weak H-bonding (N-2 and CO), medium-strong H-bonding (H2O) and proton-transfer reactions (NH3) with the Bronsted acid hydroxyl groups of zeolites and aluminophosphates (HSAPO-34 and CoAPO-18) are illustrated. The acid Lewis sites (countercations) and the acid-base couples in NaX and NaY zeolites are monitored by CO and CO2 adsorption respectively. Finally, FTIR and UV-Vis studies of the H2O and NH3 adsorption that probe the transition metal cation centres in mesoporous Ti-MCM41 and microporous CoAPO-18 catalysts are described. (C) 1999 Elsevier Science B.V. All rights reserved.